Advanced nonadiabatic ultrafast nanocalorimetry and superheating phenomenon in linear polymers

To study phase-transition kinetics on submillisecond time scale a set of new membrane gauges for ultrafast scanning nanocalorimetry were constructed. Controlled ultrafast cooling, as well as heating, up to 106 K/s was attained. The maximum cooling rate is inversely proportional to the radius of the heated region, which was in the range 10–100 μm for different gauges. The minimum addenda heat capacity was 3 nJ/K. A model describing dynamics of the temperature distribution in the membrane–gas system at ultrafast heating and cooling was developed. The characteristic rate R0 corresponding to the quasi-static limit of the temperature change in the membrane–gas system was determined. The rate R0 equals 105 K/s for the different gauges in helium gas. The new calorimetric cells in combination with common differential scanning calorimetry (DSC) were applied for the measurements of superheating in a set of linear polymers. A power law relation between the superheating and the heating rate was observed in the broad heating rate range 10−2 to 105 K/s.